An English pronunciation is "lə-TISH-ə". Source: Sheard, K.M., (2011), Llewellyn's Complete Book of Names: For pagans, witches, wiccans, druids, heathens, mages, shamans & independent thinkers of all sorts who are curious about names from every place and time, Llewellyn's Publications, Woodbury, Minnesota, USA, page 643.
In the International Phonetic Alphabet, this name's pronunciation is [le.Ti.ʦja]. This gives, according to this site's pronunciation guide, approximately "lay-tee-tsia", but with a short "ee" sound. This name is pronounced with a slight stress, if any, on the last syllable.